Some cooling systems, such as those required to cool electronic equipment, need to regulate the flow of cooling fluid through the system, so that the system doesn't provide too little or too much cooling capacity to the electronic equipment. Too little cooling will allow the electronic equipment to overheat, thereby causing underperformance by or damage to the electronic equipment or its surroundings. Too much cooling can consume too much power by the cooling system, generate condensation within the electronic equipment and/or allow unwanted phase changes to occur in the cooling fluid (e.g. if the cooling fluid is water), among other potential problems.
Some cooling systems employ flow-regulating devices, or orifices, inline with the cooling fluid path. Flow-regulating devices reduce the flow rate of the cooling fluid through the cooling system by a specified amount. Upon designing a cooling system for a given set of electronic devices, such as a rack-mounted computerized system, a flow-regulating device is selected that provides the necessary flow regulation depending on the cooling capacity of the cooling system and the anticipated level of heat generation by the electronic equipment.
If the electronic devices or a part of the cooling system is changed requiring a different flow rate, fluid velocity or static pressure for the cooling fluid, then the flow-regulating device may have to be replaced. Replacing the flow-regulating device requires turning off the flow of the cooling fluid both upstream and downstream from the flow-regulating device. Then the flow-regulating device can be removed with a minimum of loss of cooling fluid. A new flow-regulating device is inserted, the lost cooling fluid is replaced and the flow of the cooling fluid is turned back on.
Since the flow of the cooling fluid must be turned off, the electronic equipment also has to be shut down, in order to prevent overheating of and possible damage to the electronic equipment and its surroundings. However, it is costly and time consuming to go through the operation of turning off the electronic equipment, turning off the cooling system, replacing the flow-regulating device, turning on the cooling system and turning back on the electronic equipment. Depending on circumstances, a considerable interruption of business operations can result when electronic equipment, such as computer server systems, is turned off for any period of time. It is thus with extreme reluctance that information technology (IT) managers take such drastic action within an enterprise.